知识与财富的链接
中、高熵合金因很好地兼顾了强度和韧性而备受关注,在多种极端工况下具有重要的应用前景。然而,在强冲击载荷等极端条件下,其动态力学行为和损伤失效机制仍不清楚。为此,研究了NbTiZr中熵合金在平板冲击载荷下的层裂损伤,探讨了冲击应力和加载脉宽的影响。通过波剖面分析,获得了冲击应力、加载脉宽和层裂强度信息。研究表明,NbTiZr中熵合金的层裂强度随冲击应力的增大而线性增大,随加载脉冲宽度的增大呈指数减小,介于3.77～4.80 GPa之间。利用光学显微镜、扫描电子显微镜和电子背散射衍射,分析了冲击加载后回收样品的微观组织结构,发现冲击应力和加载脉冲宽度对NbTiZr的层裂损伤形貌有显著影响,层裂损伤形式为准解理断裂,未观察到固-固相变或变形孪晶。
Dynamic mechanical behaviors of high entropy alloys (HEAs) or medium-entropy alloys (MEAs) have attracted significant attention due to their exceptional strength-toughness balance and promising potential applications in extreme conditions. This work investigates the effects of peak shock stress and pulse duration on the spall damage of the NbTiZr MEA under dynamic shock loading. Peak shock stresses, pulse durations and spall strengths are determined by analyzing free surface velocity profiles, with postmortem microstructural analysis to reveal the underlying deformation and failure mechanisms. The measured spall strength of NbTiZr MEA ranges from 3.77 GPa to 4.
80 GPa, showing minimal dependence on the peak shock stress but high sensitivity to the pulse duration. Furthermore, the damage morphologies are significantly influenced by pulse durations. The damage is recognized as a quasi-cleavage fracture mode. No phase transition or deformation twins are observed within the recovered NbTiZr alloy.
